The Chemistry

THE CHEMISTRY OF' COOKING AND CLEANING. THE CHEMISTRY OF COOKING AND CLEANING A MANUAL FOR HOUSEKEEPERS ELLEN H. RICHARDS IXSTRUCTOR D! CIIE:vJ1STRY, \VOl\L<\N"S LABORATORY, MASSACHUSETTS I",ST1TUTE OF TECII:SOLOGY, I30STO:-! BOSTON ESTES & LAURIAT 301 - 305 WASHIXGTO",ST 1882 Copyright, 1881. BY ESTES & LAURIAT. PREFACE. -:0:- IN this age of applied science, every opportunity of benefiting the household should be seized upon. The family is the heart of the country's life, and every philanthropist or social scientist must begin at that point. Whatever, then, will enlighten the mind, and lighten the burden of care, of every housekeeper will be a boon. At the present time, when the electric light and the gas stove <ire farruliar topics, there is, after all, no branch of science which might be of more benefit to the community. if it were properly understood, than Chemistry - the Chemistry of Common Life, John- ston's excellent book with that title deserves a wider circulation, and a more careful study, viii PREFACE. But there is a space yet unoccupied for an elementary work which shall give to non-scientific readers some practical information as to the chemical composition of articles of daily use, and as to their action in the various operations in which they are employed. The public are the more ready for the application of this knowledge since Chemistry is taught in nearly all High Schools, and every child has a dim idea of what some part of it means. To gather up into a definite and practical form these indistinct notions is the aim of this little book. There is, lingering in the air, a great awe of chemistry and chemical terms, an inheritance from the age of alchemy. Every chemist can recall instances by the score in which manufacturers have asked for recipes for making some substitute for a well-known article, and have expected the most absurd results to follow the simple mixing of two substances. Chemicals are supposed by the multitude to be all-powerful, and great advantage is taken of this credulity by unscrupulous manufacturers. The number of patent compounds thrown upon the market under fanciful and taking names is a witness PREFACE. ix to the apathy of housekeepers. It is time that they should bestir themselves for their own protection. A little knowledge of the right kind cannot hurt them, and it will surely bring a large return in comfort and economy. These mysterious chemicals are not so many or so complicated. in structure but that a little patient study will enable anyone to understand the laws of their action, as far as they are concerned in the common operations of the household. No attempt is here made to cover the whole ground of chemical science, but only to explain such of its principles as are involved in the raising of bread, and in a few other common processes. CONTENTS. CHAP. PAGE. I. INTRODUCTION, II. STARCH, SUGAR, AND FAT, AS FOOD. 10 III. NITROGENOUS FOOD AND Tr-E CHEMISTRY OF NUTRITION, 37 PART II. 1. THE CHEMISTRY OF CLEANING, 55 II. CHEMICALS FOR HOUSEHOLD USE, 80 CHAPTER I. INTRODUCTION. WE recognize substances, as we know people, by their characters (properties) and by their appearance. Sugar we call sweet; if any- thing is sour, we call it acid. Sugar and salt dissolve in water. Carbonic acid gas will extin- guish the flame of a candle. These are properties of the several substances. A teaspoonful of sugar heated over a fire turns black, swells up to a large bulk, emits a gas which burns with a smoky flame, and finally there is left a black, crumbly mass, which seems like what it is, fine charcoal. There is nothing which we consider sugar left, no sweetness, none of the properties which we know under the name of sugar. There 2 THE CHEMISTR r OF IS a change, a loss of identity. This change is called a chemical one. Add a solution of an acid to a solution of an alkali, and observe that the acid substance 'and the alkaline substance are no longer in existence as such. There is, instead, a neutral saline substance dissolved in water. The new substance has not the properties of either of the others. The acid and the alkali have both lost their identity. A chemical change, then, involves a loss of identity. " We must be very careful not to transfer our ideas of composition, drawn chiefly from the mixtures we use in common life, directly to chemistry. In these mixtures the product partakes, to a greater or less degree, of the character of its constituents, which can be recognized, essentially unchanged, in the new material. In all instances of true chemical union and decomposition, the qualities of the substances concerned in the pro- cess entirely disappear, and wholly different substances with new qualities appear in their place."· • "The New Chemistry!'- Josiah P. Cooke. p. 99. COOKING AND CLEANING. 3 All the substances about which we know any- thing are composed of a few elementary bodies. The grain of wheat, the flesh of animals, the dangerous poison, all are capable of being sep- arated into the simple substances of which they are composed. The chemical element is that substance out of which nothing essentially different * has ever yet been obtained. Pure gold is an element, a simple substance, from which nothing can be taken different from itself. A gold coin contains a little copper or silver, or both, and is not pure gold j it is a mixture of two or more elementary substances. The oxygen in the air is an element, a single thing. Water is a compound of two elements, oxygen and hydrogen, which are gases when they exist as simple substances. There are about seventy of these elementary substances known to the chemist j about ten or twelve of them enter into the compounds which we use in the kitchen. The others are found only in the chemical laboratory or in the physician's medicine case, and a few are so rare as to be • "Treatise on Chemistry."-Roscoe & Schorlemmer, p. 51. 4 THE CHEMISTR r OF considered curiosities. Most of these elements unite with each other, and, in the compounds thus formed, other elements may exchange places with those already there, so that a few elementary bodies, by the variety of combination, make up the objects of daily use. To understand something of the nature of these chemical substances and their common forms is a necessity for every housekeeper who would not be cheated ?f her money and her time. It is important for everyone to remember that laws govern all chemical changes j' for one is often asked to believe that some chemical sleight of hand can make one pound of washing-soda worth as much as two, and that some special preparation of flour will give a third more bread than any other. As has been said, we recognize substances by their properties, and the chemical elements have two essential characteristics which must be considered at the outset of our discussion. It is assumed that they are composed of homo- geneous particles, the so-called atoms, the smallest COOKING AND CLEANING. 5 masses of matter which enter into chemical combination. The particles have a definite weight, constant for each substance. This weight is known in chemistry as the atomic weight. Hydrogen being the lightest substance yet known, its atomic weight is taken as the unit. TABLE I. NAME. SYMBOL. ATOMIC WEIGHT. Hydrogen H Sodium (Natrium) Na 23 Calcium Ca 4° Oxygen 0 16 Carbon C 12 The atom of oxygen weighs 16, and the atom of calcium 40 times as much as the atom of hydrogen. The letters or symbols in chemical forrnulse rep- resent this definite weight, so that while the word oxygen means only that collection of properties to which we give the name, the letter 0 in a formula indicates also 16 times the weight of H, which is taken as J. These symbols give a definiteness to the chemical 6 THE CHEMISTR r OF terms which words merely cannot convey, and therefore they are a great aid to the right com- prehension of the laws of combination. In a table at the end of the book will be found the atomic weight of all the elements referred to in the text. The atoms of each element have also their own value in uniting and exchanging places with the others. The unit of value is an arbitrary standard. Some- thing else might have been taken than the unit chosen, but the relative value of all the elements as compared with each other is constant. At the outposts of the Hudson's Bay Territory all trade is on a system of barter or exchange, and a basis of value is necessary. The skin of a beaver is agreed upon as the unit from which to count all values. For example: a red fox skin is worth two beaver skins, a silver fox skin IS worth four beaver skins. All of the hunter's stock is valued in this way, and also articles to be purchased are valued by the same standard, a knife is purchased for four beaver skins, a gun is worth three silver fox or twelve beaver skins. Chemists have COOKING AND CLEANING. 7 agreed upon a unit of value in exchange, and the unit thus agreed upon is the atomic weight of hydrogen above referred to j that is, the smallest relative weight of hydrogen known to enter into combination with other elements.

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